mpls sr adjacency ttl-mode

Function

The mpls sr adjacency ttl-mode command configures a mode for processing the TTL for a public network SR tunnel established using adjacency labels.

The undo mpls sr adjacency ttl-mode command restore the default TTL processing mode for a public network SR tunnel established using adjacency labels.

By default, the TTL processing mode of a public network SR tunnel established using adjacency labels is uniform.

Format

mpls sr adjacency ttl-mode { pipe | uniform }

undo mpls sr adjacency ttl-mode

Parameters

Parameter	Description	Value
pipe	Indicates the pipe mode used to process TTLs in packets transmitted over a public network SR tunnel.	-
uniform	Indicates the uniform mode used to process TTLs in packets transmitted over a public network SR tunnel.	-

Parameter

Description

Value

pipe

Indicates the pipe mode used to process TTLs in packets transmitted over a public network SR tunnel.

uniform

Indicates the uniform mode used to process TTLs in packets transmitted over a public network SR tunnel.

Views

MPLS view

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
segr	write

Usage Guidelines

Usage Scenario

TTLs in packets transmitted over SR LSPs are processed in either of the following modes:

Uniform Mode
The IP TTL value reduces by one each time it passes through a node in an MPLS network.
When IP packets enter the MPLS network, the ingress reduces the IP TTL value by one and copies the IP TTL value to the MPLS TTL field. Each transit node only processes the MPLS TTL. The egress reduces the MPLS TTL by one, compares the MPLS TTL with the IP TTL, and obtains the smaller value to map it to the IP TTL.
Pipe Mode
The IP TTL value decreases by one only when passing through the ingress and egress.
The ingress reduces the IP TTL value in packets by one and sets the MPLS TTL to a specific value. Transit nodes only process the MPLS TTL. When the egress receives the packets, it removes the MPLS label carrying the MPLS TTL from each packet and reduces the IP TTL value by one.
When Virtual Circuit Connectivity Verification (VCCV) tracert is used to trace routes of MS-PWs, all nodes on an LSP must use the same TTL processing mode. A mode inconsistency causes a tracert failure.

When the public network SR tunnel is established using the Adjacency label, it is controlled by the command and supports the uniform or pipe modes.

Example

# Configure the device to process TTLs in packets transmitted over an SR-LSP in pipe mode.

<HUAWEI> system-view
[~HUAWEI] mpls
[*HUAWEI-mpls] mpls sr adjacency ttl-mode pipe